This invention relates to gas fired artificial log assemblies. More particularly, it relates to gas fired artificial log assemblies which are used in unvented environments.
Woodburning fireplaces have been used for many years by homeowners to provide heat, as well as to provide an aesthetically pleasing home environment. All woodburning fireplaces, however, require venting of the products of combustion through a chimney, otherwise deadly fumes, such as carbon monoxide, will build up in the house and can cause illness, and even death. Obviously, a chimney requires a substantial capital expenditure.
In addition, use of woodburning fireplaces require the user to haul wood into the house, light the fire, and maintain the fire. In addition, woodburning fireplaces require the user to maintain an adequate source of wood which must be kept dry in order to be useful.
More recently, homeowners have turned to artificial logs which are fired with either natural gas or propane as a substitute for woodburning fireplaces. Gas fired artificial log systems are clean and efficient, easy to use, and require almost no maintenance. In addition, newer artificial log systems provide for a yellow flame flicker which provides a substantial duplication of the warm appearance of a natural wood fire. Artificial logs made of ceramics will actually glow giving the appearance of glowing embers. However, heretofore, most artificial log systems continue to be vented through a chimney arrangement in a very similar fashion to a woodburning fireplace. In fact, many artificial log systems are simply retrofits of a woodburning fireplace.
More recently it has been found that because natural gas and propane are very clean burning materials, gas fired artificial logs may be used in an unvented environment. However, because any combustion in a room utilizes oxygen as a component necessary in the combustion, as a safety factor oxygen depletion sensors are required which will automatically shut off the gas valve and thus the gas to the log should oxygen reach a certain low level in the room.
The only control system known to applicant which is used in an unvented situation are the systems like the one manufactured by Sourdillon of Vigne, France. Those systems utilize a pilot which is integrated with a oxygen depletion sensor. The pilot is fed by a manually operated gas valve which also feeds a main burner. A low voltage (32 millivolts) thermocouple is positioned a predetermined distance and slightly below the pilot. The thermocouple is tied to the valve so that if the pilot is extinguished due to low oxygen, the valve will shut off the gas to the pilot as well as to the main burner.
This type of thermocouple control system is capable of producing only 32 millivolts and thus may not be used to control a fully automatic gas valve such as one made by ITT's General Controls Division (Catalog No. B67RA01). The ITT valve is capable of fully automated operation, i.e., it may be used in conjunction with a thermostat to sense the room temperature and turn the main valve off and on and also may be used with infrared remote controls.
Thus, there is a need for a fully automatic gas log system which may be used in unvented environments.